In short
Small fibre neuropathy affects the tiny nerve fibres that carry pain and temperature and control automatic body functions. It typically causes burning feet, tingling and sensitivity. Standard nerve conduction tests are often normal, so diagnosis can need a skin biopsy or other specialised tests.
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What is small fibre neuropathy?
Nerves contain fibres of different sizes. Large fibres carry touch, vibration and position sense, and control muscles. Small fibres carry pain and temperature sensations, and also help control automatic functions such as sweating, heart rate and digestion. Small fibre neuropathy (SFN) is damage that mainly affects these small fibres.
Symptoms
- Burning, stabbing or prickling pain, often starting in the feet
- Tingling, pins and needles, or a feeling of tightness in the skin
- Sensitivity to touch, such as bedsheets on the feet
- Reduced ability to feel heat, cold or pain
- Restless or uncomfortable legs at night
- Autonomic symptoms, such as changes in sweating, dizziness on standing, dry eyes or mouth, or bowel and bladder changes
Strength and reflexes are usually normal, which is one reason SFN can be missed.
Nerve pain getting in the way?
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How is it diagnosed?
Standard nerve conduction studies test large fibres, so they are often normal in SFN. Diagnosis usually combines:
- your symptoms and an examination of pain and temperature sensation
- a skin biopsy, usually from the lower leg, to count the small nerve fibres
- specialised tests of sensation or sweating in some clinics
- blood tests to look for causes
Diagnosis often involves a neurologist.
Causes
- Diabetes and prediabetes
- Vitamin B12 deficiency
- Thyroid disease and some autoimmune conditions
- Heavy alcohol use
- Some infections and some medicines
- Inherited conditions, in a small number of people
In many people, no cause is found despite testing.
Management
- Find and treat any underlying cause
- Manage nerve pain, which may include medicines that act on the nervous system
- Look after sleep, activity and mood
- Protect numb skin from burns and injuries
The outlook varies. When a treatable cause is found and managed, symptoms can stabilise or improve.
When to see a GP
See a GP if you have burning or tingling feet, unexplained pain sensitivity, or dizziness and sweating changes alongside these symptoms. Your GP can arrange blood tests and a referral to a neurologist.
Next step: talk to a doctor
Answer a few quick questions and you’ll get an email about your eligibility. A consultation doesn’t guarantee any particular treatment.
References
- Sopacua M, Hoeijmakers JGJ, Merkies ISJ, et al. Small-fiber neuropathy: Expanding the clinical pain universe. J Peripher Nerv Syst. 2019;24(1):19-33.
- Colloca L, Ludman T, Bouhassira D, et al. Neuropathic pain. Nat Rev Dis Primers. 2017;3:17002.
- Feldman EL, Callaghan BC, Pop-Busui R, et al. Diabetic neuropathy. Nat Rev Dis Primers. 2019;5(1):41.
This guide is general information, not medical advice. It doesn’t replace a consultation with a doctor who knows your history. In an emergency, call 000.